1. Field of the Invention
This invention relates to a new process sequence for cleaning processing equipment for beverages or foods in the corresponding processing plants. Examples of such processing plants include milk-processing factories, breweries, factories for processing fruit juices and for the manufacture of preserved and deep-frozen foods. The new process affords economic and ecological advantages through an integrated recycling step.
2. Discussion of Related Art
The so-called cleaning-in-place (CIP) concept has been successfully adopted for the cleaning of such plants. This means that the equipment designed to receive and process foods or beverages is provided with its own installed cleaning system. The cleaning system generally consists of several storage containers for cleaning solution, for prerinse and post-rinse solutions and optionally for soiled water flowing back. The individual cleaning solutions are delivered to the equipment to be cleaned through valve-controlled pipes and are optionally pump-circulated up to the end of the cleaning process. The cleaning solutions themselves may either be strongly acidic or strongly alkaline, i.e. may have pH values of, for example, about 0 to about 2 or in the range from about 12 to about 14. Besides the acids or alkalis, for example sodium hydroxide, the cleaning solutions optionally contain other additives such as, for example, surfactants, defoamers, complexing agents and disinfectants. "Neutral" cleaners with a pH value in the range from about 4 to about 9 are also possible.
In the cleaning-in-place of processing equipment in the food- or beverage-processing industry, the emptied equipment is normally prerinsed with water to remove residues of product. The water soiled with the product residues is normally discharged into the main drains and is therefore lost to the rest of the process. Accordingly, the prerinse step costs water, time and also energy.
The prerinse step is normally followed by the actual cleaning phase in which the cleaning solution is pumped from its holding tank through the equipment to be cleaned and back into the holding tank. The cleaning solution circulates until the required cleaning effect is achieved. It becomes increasingly polluted by the soil removed from the processing equipment and, after a short time, has to be discarded or treated. In recent years, regeneration systems such as, for example, Alka Save or Niro Filtration Systems have been brought onto the market for treating the soiled cleaning solution. In these regeneration processes, soil components are removed from the cleaning solution so that its useful life is extended. However, this does not affect the actual cleaning process consisting of the prerinse, cleaning and post-rinse steps.
The actual cleaning phase is followed by rinsing with water to remove all traces of the cleaning solution from the processing equipment. The rinsing water accumulating contains residues of the cleaning solution and soil residues and, to save water, may be used as the prerinse solution as described in the foregoing. However, the tendency to reuse this water is on the decline for several reasons. There is a danger of microorganisms adapting to the cleaning and disinfecting chemicals present in the rinsing water. The germs present in the rinsing solution and in the corresponding storage tank proliferate and soil components accumulate. Accordingly, germs and soil are additionally introduced into the equipment to be cleaned in the prerinse step. This adversely affects the starting situation for cleaning and disinfection. If an acidic cleaning solution is used, the pH value of the rinsing solution is often around the isoelectric point of the proteinaceous soil to be removed. This makes cleaning very difficult.
The problem addressed by the present invention was to improve the cleaning-in-place process in such a way that the water, time and energy demands would be reduced and, in addition, the soil removed from the processing equipment would accumulate in a concentrated form so that it would be easier to treat or dispose of as waste.